/*
 * Copyright 1999-2018 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cn.springmix.core.utils;

import lombok.Data;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.concurrent.ListenableFuture;
import org.springframework.util.concurrent.SettableListenableFuture;

import java.util.List;
import java.util.Objects;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.TimeUnit;
import java.util.function.Supplier;
import java.util.stream.Collectors;

/**
 * @author Eric Zhao
 * @since 1.4.1
 */
public final class AsyncUtils {

    private static final Logger LOG = LoggerFactory.getLogger(AsyncUtils.class);

    private AsyncUtils() {
    }


    public static <R> CompletableFuture<R> newFailedFuture(Throwable ex) {
        CompletableFuture<R> future = new CompletableFuture<>();
        future.completeExceptionally(ex);
        return future;
    }

    public static <R> CompletableFuture<List<R>> sequenceFuture(List<CompletableFuture<R>> futures) {
        return CompletableFuture.allOf(futures.toArray(new CompletableFuture[0]))
                .thenApply(v -> futures.stream()
                        .map(AsyncUtils::getValue)
                        .filter(Objects::nonNull)
                        .collect(Collectors.toList())
                );
    }

    public static <R> CompletableFuture<List<R>> sequenceSuccessFuture(List<CompletableFuture<R>> futures) {
        return CompletableFuture.supplyAsync(() -> futures.parallelStream()
                .map(AsyncUtils::getValue)
                .filter(Objects::nonNull)
                .collect(Collectors.toList())
        );
    }

    public static <T> T getValue(CompletableFuture<T> future) {
        try {
            return future.get(10, TimeUnit.SECONDS);
        } catch (Exception ex) {
            LOG.error("getValue for async result failed", ex);
        }
        return null;
    }

    public static boolean isSuccessFuture(CompletableFuture future) {
        return future.isDone() && !future.isCompletedExceptionally() && !future.isCancelled();
    }

    /**
     * 返回ListenableFuture回调成功与异常
     * 主要是屏蔽CompletableFuture细节
     *
     * @param supplier 上层提供的业务逻辑
     * @param <T>      上层提供的参数。成功时利用唯一表示来做后置处理
     * @return addCallback 带回调的ListenableFuture
     */
    public static <T> ListenableFuture<Resp<T>> createFuture(Supplier<T> supplier) {
        SettableListenableFuture<Resp<T>> slf = new SettableListenableFuture<>();
        Resp<T> resp = new Resp<>();
        CompletableFuture.supplyAsync(() -> {
                    //带回调的业务逻辑
                    resp.setResult(supplier.get());
                    return true;
                }, ThreadUtil.getCpuIntenseTargetThreadPool())
                .thenApply(aBoolean -> {
                    resp.setOk(aBoolean);
                    slf.set(resp);
                    return slf;
                }).exceptionally(throwable -> {
                    slf.setException(throwable);
                    return null;
                });
        return slf;
    }

    public static void main(String[] args) throws Exception {
        ListenableFuture<Resp<String>> future = createFuture(() -> {
            System.out.println("执行业务逻辑 返回业务id");
            return "1";
        });
        future.addCallback(result -> {
            System.out.println("成功" + result.toString());
        }, ex -> {
            System.out.println("异常" + ex);
        });
        System.out.println("挂起主线程");
        Thread.currentThread().join();
    }

    @Data
    public static class Resp<T> {
        private T result;

        private boolean ok;
    }
}
